- Paleocene: explosive evolutionary radiation
of mammals fills ecological niches vacated by the dinosaurs
from shrew-like mammals of the Cretaceous, 22 mammalian orders
(almost all the modern orders) evolved by the Eocene, including the
familiar groups: bats, whales, hoofed animals, carnivores, rodents,
and primates
- grasses evolved
- animals adapt to expansive savanna conditions in the Eocene following global cooling that ended the tropical/subtropical conditions of the Paleocene and Eocene
- Oligocene: earliest true apes - Egypt
- Pliocene: earliest hominids, Australopithecus in east Africa, ~4 m.y.
- Pleistocene: earliest genus homo, ~1.75 m.y., Olduvai Gorge, Tanzania
- Homo sapiens arose 500,000 to 300,000
yrs ago (Neanderthals)
modern humans (Homo sapiens sapiens) first evolved around 150,000
years ago; they were first seen in Europe by 40,000 years ago where
they coexisted with Neanderthals for over 5,000 years
humans crossed Bering Land Bridge to North America 20,000 to 30,000 years ago during low sea level of last ice age; spread southward after glaciers broke up around 10,000 years ago
- early civilizations arose during the last interglacial, since the climatic optimum (beginnings of Egyptian and Mesopotamian civilizations 6000 to 8000 yrs ago)